Upgrade to 1.0.0-rc883

Concerns: pushword/core

pw:image:cache -p counts the images its workers reported

A parallel run derived its processed count as stale images - errors, so a worker that exited having done nothing was still credited with its whole batch. The parent now counts the per-image lines each worker prints: an image no worker accounted for is reported as an error instead of assumed done, and a failure inside a batch arrives named rather than as batch: exit code 1.

Affected: sites running with -p above 1, or on 8 cores or more, where the automatic worker count is already above 1. Expect the number to drop, and a run that was silently losing a batch to now exit 1. The rc882 note called this path already correct; it was not.